Artists of the 19th Century such as Cassatt, Degas, Morisot and Renoir, to name only a few, worked with pastels. Increasingly pastels of this period are in need of treatment, to a point where they represent one of the major problems in art conservation today. Works of art in pastel are inherently unstable. This is because the pastel medium consists of dry pigment particles held together with a binder. The sole purpose of the binder, most commonly gum tragacanth, is to hold the pigment particles together in order to form a stick which is used to apply the pastel pigments to the paper or other substrate which forms a vehicle for the work of art. The adhesion of the pastel pigment particles to the substrate, which usually is paper, depends largely on the degree of pressure exerted by the artist on the stick during the execution of the work, and surface texture of the paper or substrate. Inherently, the pastel is extremely fragile and the pastel particles have a natural tendency to flake off from the paper substrate. Once the pastel particles have been applied to the substrate, virtually any condition which affects the weak adhesive forces holding the particles to the substrate causes damage to the piece and a subsequent loss of pigment. For example, vibration of a pastel work during travel or extensive handling, hygroscopic activity of the paper or substrate, and even the electrostatic charges which are present if the work is improperly framed with acrylic rather than glass, all will contribute towards the deterioration of the pastel.
The use of fixatives is not satisfactory in the case of pastels for a variety of reasons. One of the reasons is the irreversibility of fixatives with respect to pastels, since the fixatives cannot be removed without total destruction of the work. Another reason militating against the use of usual fixatives is the undesirable changes in overall color balance and color relationships which occur when known fixatives are applied to a pastel work. Still other reasons include the undesirable alteration of the surface of a pastel by known fixatives, aging characteristics of known fixatives requiring their removal in time which, as stated, would destroy the pastel, and adverse effects on the pastel due to the pH of known fixatives. It is well known in the arts, and to art conservators, that the fixing of pastels, or other friable materials, such as charcoal or graphite, is a completely irreversible process with many complications. In fact, manufacturers of pastels in many instances specifically do not recommend the use of fixatives.
In accordance with the concepts of the process of the present invention, by creating an electrostatic attraction between the pastel particles and the paper or other substrate of the work, the existing pastel works of art may be stabilized in their original condition on the substrate without exposing the works to any irreversible fixative processes.